1. Field of the Invention
The present invention relates to a tubular vibration-damping device for use, for example, in automotive differential mounts, engine mounts, body mounts, member mounts, and the like.
2. Description of the Related Art
Conventionally, tubular vibration-damping devices have been known as one type of vibration damping connecting components interposed between components that make up a vibration transmission system in order to provide vibration damping linkage between the components. The application of such tubular vibration-damping devices to a differential mount and the like wherein the vehicle body (sub frame) supports an automotive differential gear in a vibration-damping manner, for example, has been studied. As shown in U.S. Publication No. US 2014/0210148 or the like, for example, this tubular vibration-damping device has a structure in which an inner shaft member and an outer cylindrical member are elastically connected by a main rubber elastic body.
For the tubular vibration-damping device disclosed in US 2014/0210148, the axially center portion of the inner shaft member is provided with a stopper member including a pair of first stopper protrusions and a pair of second stopper protrusions that protrude in axis-perpendicular directions orthogonal to each other. The stopper protrusions are abutted on the side of the outer cylindrical member in each of the axis-perpendicular directions, thus constituting stoppers limiting the relative displacement amount between the inner shaft member and the outer cylindrical member. Consequently, the durability of the main rubber elastic body improves.
The main rubber elastic body is fixed on the first stopper protrusion, while the outer peripheral rubber stopper formed integrally with the main rubber elastic body is fixed on the protruding tip face of the first stopper protrusion. This moderates striking noise etc. during the contact between the first stopper protrusion and the side of the outer cylindrical member.
However, as a result of the inventors' study about the tubular vibration-damping device disclosed in US 2014/0210148 on the assumption of a larger input load, the inventors got a finding that further improvement of the durability is preferable. Specifically, with the structure of US 2014/0210148, the main rubber elastic body and an outer peripheral rubber stopper are integrally formed and both of them are fixed to the first stopper protrusions. In addition, a portion of the outer peripheral rubber stopper where the stopper load is input is disposed continuously at a position close to the main rubber elastic body. As a result, if cracking occurs in the outer peripheral rubber stopper by the input of the large stopper load, the cracking in the outer peripheral rubber stopper is thought to spread to the main rubber elastic body provided continuously in the proximity of the outer peripheral rubber stopper, which may affect the durability of the main rubber elastic body adversely.